Dibenzimidazole-diureas

ABSTRACT

Dibenzimidazole-diurea compounds corresponding to the formula:   WHEREIN R1 and R2 are hydrocarbyl radicals and R3 is a hydrocarbylene radical, are highly efficacious grease thickening agents.

United States Patent [191 Birke Feb. 18, 1975 DIBENZIMIDAZOLE-DIUREAS [75] Inventor: August G. Birke, Godfrey, Ill.

[73] Assignee: Shell Oil Company, New York, NY.

[22] Filed: Aug. 9, 1973 [21] Appl. No.: 386,910

Related US. Application Data [62] Division of Ser. No. 169,460, Aug. 5, 1971, Pat. No.

[52] US. Cl. 260/3092 [51] Int. Cl C07d 49/38 [58] Field of Search 260/3092 [56] References Cited UNITED STATES PATENTS 3,222,285 12/1965 Rai et al. 252/l37 3.752.765 8/1973 Birke 252/51.5 A

Primary ExaminerHenry R. Jiles Assistant Examiner-C. M. S. .laisle Attorney, Agent, or Firm-Leonard P. Miller; Henry C. Geller [57] ABSTRACT Dibenzimidazole-diurea compounds corresponding to the formula:

wherein R and R are hydrocarbyl radicals and R is a hydrocarbylene radical, are highly efficacious grease thickening agents.

5 Claims, N0 Drawings DIBENZIMIDAZOLE-DIUREAS This is a division of application Ser. No. 169,460, filed Aug. 5, l97l, now US. Pat. No. 3,752,765, patented Aug. 14, I973.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a novel class of dibenzimidazole-diurea compounds and grease compositions gelled therewith.

2. Description of the Prior Art It has become increasingly important that grease compositions be able to provide adequate lubrication SUMMARY OF THE INVENTION It has now been found that grease compositions having excellent high temperature lubricating properties can be produced by incorporating into an oleaginous base vehicle, a minor amount of a dibenzimidazolediurea compound corresponding to the formula:

at high temperatures, e.g., temperatures of 350F to 450F or higher. Numerous thickening agents have been proposed for use in such greases including soap base thickeners, inorganic clay thickeners and organc thickening agents. Examples of this latter class ofthickening agents include various polyurcas, ureido compounds, aminoaryl diureas, triazines and the like. Such organic thickening agents are typically prepared by reacting one or more mono-, di-, or polyamines with one or more mono-, di-, or polyisocyanates. Other related organic thickeners include arylcarbamyl compounds formed by reacting an aromatic amine with the reaction product of an aromatic diisocyanate and paminobenzoic acid.

While organic thickening agents of the aforementioned types produce greases having desirably high dropping points, this is but one measure of a greases ability to perform satisfactorily at high temperatures. Other important properties include thermal and mechanical stability, high temperature bearing performance, oxidation and corrosion resistance, etc. While additives are normally incorporated into grease compositions to improve one or more of these properties, the

thickening agent itself can significantly affect, either wherein R, and R are hydrocarbyl radicals and R is a hydrocarbylene radical. (By hydrocarbyl or hydrocarbylene is meant monovalent or divalent organic radicals, respectively, comprising solely carbon and hydrogen. Such radicals may be aliphatic, acyclic or aromatic, or partially aliphatic and partially aromatic, e.g., alkaryl or aralkyl.) Not only do the grease compositions of the invention have high dropping points, but in addition they have excellent mechanical and thermal stability, and high temperature bearing performance properties as well. These excellent qualities are believed attributable in large part to the unique dibenzimidazole structure of the present thickening agents which produces an extremely stable molecule.

DESCRIPTION OF THE PREFERRED EMBODIMENTS favorably or adversely, the properties of the finished 45 and further reaction with two moles of a monoisocyagrease product. Thus, in spite of the numerous organic nate. This procedure is illustrated by the following thickening agents known in the art, there is a continuequations:

Equation 1 ,NO; NR NO: N N N0 0 O O 2 2 Q 01 :c c-m-c NH: R: N/ \N or H H OH OH I O l l 0 C R C Equation 2 NO N i N No: NH N N in s a a l C-RrC H= c-R c Hm, N N N N H H II II Equation 3 NH; N N Na,

- R,-Nc

9 3 N N a H o H 9 H m-N-c- -c-N-R An alternative method of preparaing the bisnitrobenzimidazole produced in Equation 1 is to react the dicarboxylic acid or its anhydride with two moles of a phenylene diamine which is not nitro-substituted. The resultant product can be subsequently nitrated to produce the bis-nitrobenzimidazole, which is then converted to its amino form and reacted with two moles of the monoisocyanate as shown in Equations 2 and 3 above. A more detailed description of the preparation of the dibenzimidazole-diurea thickeners is given in the examples.

Dicarboxylic acids or anhydrides which can be suitably employed in preparing the thickeners of the invention include the acids or anhydrides of aliphatic dicarboxylic acids such as succinic, glutaric, adipic, pimelic, suberic. azelaic, sebacic acids or anhydrides, as well as aromatic dicarboxylic acids such as phthalic, isophthalic or terephthalic acids or anhydrides or their esters. Cyclohexanedicarboxylic acids or anhydrides are likewise suitable, e.g., 1,2- or 1,4-

cyclohexanedicarboxylic acid or anhydride, and also tetrahydrophthalic acid or anhydride. Hydrocarbyl substituted dicarboxylic acid and anhydrides can also be employed, for example, alkylor alkenyl-substituted succinic anhydrides corresponding to the formula wherein R is an alkyl or alkenyl substituent of from 1 to l6 carbon atoms or more. Aliphatic dicarboxylic acids or anhydrides are preferred, and in general are selected so that the R radical of the previously depieted formula has from 2 to 20, preferably from 2 to l2 carbon atoms.

Phenylene diamines suitable for preparing the thickening agents of the invention are those having amino groups in the ortho position, i.e., o-phenylene diamines. When the thickening agents are prepared in accordance with Equation 1, o-phenylamine diamines having a nitro substituent must be employed, e.g., 4-nitro-o-phenylene diamine. In addition to the nitro substituent, o-phenylene diamines having other substituents, e.g., alkyl or halo substituents, can also be employed provided that such substituents do not appreciably interfere with the reaction of the phenylene diamine with the dicarboxylic acid 'or anhydride.

Phenylene diamines employed in accordance with the alternative procedure discussed above need not contain a nitro substituent since the addition of the nitro groups is accomplished subsequent to formation of the bis-benzimidazole. Hence, when this method of preparation is employed, unsubstituted o-phenylene diamine may be utilized or any other o-phenylene diamine having substituents which will not appreciably interfere with the formation of the bis-benzimidazole intermediate or its subsequent nitration. Examples of such phenylene diamines include 4-chloro-o-phenylene diamine and 3,4-toluene diamine.

Monoisocyanates which may be employedin accordance with the invention include aliphatic monoisocyanates or aromatic monoisocyanates having at least one aliphatic substituent of eight or more carbon atoms. Preferred monoisocyanate reactants include straight or branched chain, saturated or unsaturated aliphatic monoisocyanates having from 6 to 30, and more preferably from 12 to 24, carbon atoms. Examples of such isocyanates include cyclohexyl isocyanate, octyl isocyanate, decyl isocyanate, dodecyl isocyanate, tetradecyl isocyanate, pentadecyl isocyanate, hexadecyl isocyanate, heptadecenyl isocyanate, octadecyl isocyanate, octadecenyl isocyanate, eicosyl isocyanate. docosyl isocyanate, tetracosyl isocyanate and the like. Mixtures of the aforementioned isocyanates can also bs employed including mixtures of saturated and unsaturated aliphatic isocyanates. Aliphatic isocyanates having 16 to 18 carbon atoms and mixtures thereof are particularly preferred. The R and R radicals in the aforementioned formula are derived from the monoisocyanate reactant.

The thickening agents of the invention are generally employed in grease compositions in an amount sufficient to gel the oleaginous base vehicle to grease consistency. This amount can vary, for example, from about 5-50 percent by weight of the total composition. Normally, however, thickener concentrations of l()-35 percent by weight are sufficient to impart the desired consistency of the inventive compositions.

A wide variety of lubricating oils may be employed as the base vehicle in the present compositions. Suitable base oils include mineral lubricating oils such as naphthenic base, paraffin base or mixed base oils having a viscosity in the range of from 50 SSU at F to 300 SSU at 210F; synthetic hydrocarbon oils such as oligomerized alpha-olefins and oils derived from coal products; synthetic oils such as alkylene polymers, alkylene oxide-type polymers. polyalkene glycols, polyethers, phosphate esters, dicarboxylic acid esters and pentaerythritol esters. The above oils may be used individually or in mixtures thereof, wherever miscible or made so by the use of solvents. Of the aforementioned base oils, mineral lubricating oils having viscosities of from about 400 to 700 SSU at lO0F are especially preferred.

In addition to the dibenzimidazole-diurea thickeners, the present compositions can also contain anticorrosion additives such as disodium sebacate, glyceryl monooleate, sodium sulfonates, sodium nitrite, aminoand benzo-triazoles, and isostearamides or imidazolines of tetraethylenepentamine; oxidation inhibitors such as phenyl-alpha-naphthylamine, phenyl-betanaphthylamine, diphenylamines, phenothiazine, dithio carbamates and various analogs and homologs thereof; viscosity index improvers such as methacrylate polymers and copolymers; extreme pressure agents, and any other additive recognized in the art to perform a particular function or functions.

The following examples illustrate the method of preparation of the present thickeners and their excellent properties. It is to be understood, however, that these examples are presented for illustrative purposes only and that the invention in its broader aspects should not be limited thereto.

EXAMPLE I A 4liter round bottom flask was charged with 302.2 g (2 moles) of 4-nitro-o-phenylene diamine, 100.0 g (l mole) of succinic anhydride and 2 liters of4 normal hy drochloric acid solution. The flask and its contents were then refluxed, with stirring, for 24 hours. Heating was discontinued and the reactants were cooled to C, filtered, and the filtrate was discarded. The precipitate was collected and neutralized with 1.500 ml of normal ammonium hydroxide solution, refiltered, and washed twice with water. The neutralized material resulting was dissolved in refluxing ethylene glycol, treated with decolorizing charcoal, filtered and the fil trate cooled. The crystalline precipitate that appeared was collected, washed with ethanol and dried. The

-yield was 65 grams of l,2-bis(5-nitrobenzimidazoyl- 2)ethane having a melting point of 305C.

50.04 g (016 mole) of the above product was then suspended in 1.200 ml of 3 normal hydrochloric acid solution to which was added palladium on charcoal catalyst and reduction of the nitro groups effected in a low pressure hydrogenation apparatus. The catalyst was then filtered off, the filtrate neutralized with sodium bicarbonate and the resulting precipitate collected. After washing with water and drying, 41.5 g of l.2-bis(5- aminobenzimidazoyl-Z)ethane was obtained having a melting point of l54-l C.

14.62 g (0.05 mole) ofthe above material was placed into a 500-ml resin flask equipped with a mechanical stirrer together with 30 g (0.1 mole) of a 70:30 molar ratio octadecyl isocyanate:hexadecylisocyanate 'mix ture in 253 g of HVl-SOO Neutral oil. This suspension was heated with stirring, under nitrogen, to 127C. Upon completion of the reaction, the contents were cooled to approximately 1 lOC and then milled three times in a three-roll paint mill. The resulting grease had an ASTM dropping point of 510F, and an ASTM worked penetration strokes) of 272.

EXAMPLE it A series of grease compositions containing various dibenzimidazole-diurea thickening agents in accordance with the invention were prepared employing a variety of base vehicles. The reactants employed in the preparation of the respective thickeners and the properties of the grease compositions gelled therewith are presented in Table l.

EXAMPLE [ii In order to demonstrate the excellent high temperature performance characteristics of dibenzimidazolediurea-thickened grease compositions, several of the greases of Example ll containing conventional oxidation and corrosion inhibitors were subjected to the Navy High Speed Bearing Test as described in Federal Test Method 33 l l and to the Pope Bearing Test as de- Table l Reactants ASTM Grease Acid or Phenylene Base Thickener ASTM Penetration Droppigtg Composition Anhydride Diamine Isocyanate Oil Cone, /rwt Un\vorkcd(P.,) Worked( P Point F l Succinic 4-Nitro-omole C NH NCO A 15 250 272 5 It) anhydride phenylene 30% mole C .;H:,;,NCO

diamine 2 Succinic 4-Nitro-o- 7071 mole C H NCO C 18 8 283 513 anhydride phenylene 30% mole C H NCO diamine 3 Succinic 4-Nitro-omole C H NCO B 14 290 279 514 anhydride phenylene diamine 4 Succinic 4-Nitro-olOOZmole C H NCO B l l 260 250 501 anhydride phenylenc diamine 5 Adipic acid 4-Nitro-o 70% mole C H NCO B 15 275 2% phenylene 30 /zmole C H NCO diamine a Succittic 4-Nitroo- 63%mole C H NCO A 14 79 253 anhvdridc phenylene 277rmole C H NCO diamine l0 /zmole C H NCO 7 Succinie 4-Nitro-o- 70% mole C H NCO D 10 234 285 anhydride phenylene 30 /zmole C H NCO diamine 8 Suecittic 4-Nitro-o- 709tmole C H NCO E l5 253 234 anhydride phenylene 30% mole C H-nNLO diamine V Slltt'ltttt lNlltno lllll'iumlv(' H NPU In o nulnilt lllC phrutlcllt diamine Base il A Mineral lubricating oil having a viscosity of 500 SSU at lUU'T. llase OH H Mineral lubricating oil having a viscosity or 70 SSU at 210%. Base ()il L ()ligomeri/ed alpha-olefin synthetic hydrocarbon oil having a viscosily of 7.7 centistokes at 2 l0h Bast. ()il l) Mineral lubricating oil halving zt viscosity of 430 SSU at l00l-'. Base ()il E Mixture of hexadccyl isostearate and dimer acid esters.

scribed in Federal Test Method Standard 79 la, Method 333. The bearing life in these tests is expressed in hours and represents the length of time until bearing failure occurred. Test results are recorded in the following table.

Table II Grease Composition 6 Grease Test Procedure Composition 1 Navy High Speed Bearing Test 300F, 10.000 rpm,

Bearing Life, hrs. 3,388 4.871

Pope Bearing Test, 350F. Bearing Life. 405

hrs.

Includes l'.l \vt. phen vl-a|pha-naphthylamine. 0.55? Oronite 250 (dilauryl selenide). li wt. sodium sebacate and 0.037: wt. 3-aniino-l.2.4-tria2ole. Average of two runs.

EXAMPLE IV Other dibenzimidazole-diurea thickeners and greases in accordance with the invention include those indicated in the following table.

See footnote to Table l.

EXAMPLE v During the preparation and testing of various greases based on the present thickening agents, it was found that the dibenzimidazole-diurea compounds of the invention exhibit quite remarkable oxidation inhibiting activity when employed in conjunction with alkyl phenol or aryl amine-type antioxidants, particularly dior tri-alkyl phenols and phenyl naphthylamines. This beneficial effect is demonstrated by the results presented in Table lV which were obtained by subjecting samples of a mineral base oil containing the concentrations of antioxidants and thickening agent indicated in the table to an Air Oxidation Test at 350F. In this test 9 liters of air per hour pass through g of the test sample to which is added 20 ppm of soluble iron. The emergent air, after removal of contaminants, is passed through an oxygen analyzer which records the oxygen content of the air. Using a reference air stream, the rate of oxygen uptake is calculated. The test result which is called an induction period is defined as the time in hours required for l millimole of oxygen to be absorbed by the sample. A sample temperature of 350F was used in these tests.

'I.o-Di-tertiary-hutyI-Jqnethyl phenol "O 'lated phenyl-alphaamphthylaminc "'l'hickener ol' Grease Composition l I claim as my invention: 1. A dibenzimidazole-diurea compound corresponding to the formula:

wherein R and R are hydrocarbyl radicals having 6 to 30-carbon atoms and R is a hydrocarbylene radical having from 2 to 20 carbon atoms.

2. The compound of claim 1 wherein R and R are aliphatic hydrocarbyl radicals having from l2 to 24 carbon atoms.

3. The compound of claim 2 wherein R is an alkylene radical having 2 to 12 carbon atoms.

4. The compound of claim 3 wherein the R and R radicals have from 16 to l8 carbon atoms.

5. The compound of claim 4 wherein R is ethylene and R and R are hexadecyl, octadecyl or heptadecenyl. 

1. A DIBENZIMIDAZOLE-DIUREA COMPOUND CORRESPONDING TO THE FORMULA:
 2. The compound of claim 1 wherein R1 and R2 are aliphatic hydrocarbyl radicals having from 12 to 24 carbon atoms.
 3. The compound of claim 2 wherein R3 is an alkylene radical having 2 to 12 carbon atoms.
 4. The compound of claim 3 wherein the R1 and R2 radicals have from 16 to 18 carbon atoms.
 5. The compound of claim 4 wherein R3 is ethylene and R1 and R2 are hexadecyl, octadecyl or heptadecenyl. 